1. Field of the Invention
The invention relates to an apparatus or device for testing and evaluating the condition of endoscopes.
Endoscopy, as a method of examining bodily openings or cavities using tube-or hose-shaped optical systems, has acquired great importance in medicine. Using this technology, the attending physician is able to view organs, mucous membranes, suspect tissues and the like without surgery or by means of very small, minimally invasive surgical incisions in the body of the patient. The images obtained in this way often provide the basis for a treatment method which sometimes makes a more risky surgical procedure unnecessary. If an operation is unavoidable, the so-called intraoperative endoscopy serves the surgeon as an indispensable tool during the procedure.
Due to preparatory procedures such as sterilization, etc., which must be performed prior to their use, endoscopes used in endoscopic procedures are subjected to great stress. Practical experience has shown that the quality of the image worsens over extended periods of use and the images generated become milky or cloudy.
An example of some of the causes of cloudy images in rigid endoscopes containing a rigid sleeve tube with rod lenses is a lens fracture caused by mechanical damage to the sleeve tube. The rod lenses which measure up to 50 mm are often brittle and are therefore easy to break, so that even slight deformations of the sleeve tube can degrade the imaging quality of the endoscope. Lens fractures often occur even when no apparent mechanical damage such as warping or dents can be observed on the sleeve tube.
In addition to lens fractures, deteriorations in image quality are caused by a clouding of the optical system. Tiny dirt particles and deposits of contaminants which have entered the endoscope through areas that are not leak-proof, settle on the optical components and thereby change optical parameters such as transmission, contrast and image sharpness. Extreme fluctuations in temperature, for instance, to which an endoscope is often exposed during sterilization, cause subtle movements by the rod lenses and the spacer sleeves which are arranged between the rod lenses with respect to the sleeve tube. The results are wear and tear in the form of material being abraded. In addition, adhesives used to join the rod lenses tend to become opaque at high temperatures and so also impair the quality of the image.
In practice, it is useful to differentiate between the deterioration of image quality which results from mechanical damage and the type caused by natural wear and tear during the normal and proper use of the endoscope. With regard to service claims arising from warranty contracts, it would for instance be desirable to have a testing process which would make it possible to differentiate between the aforementioned causes of damage. A further meaningful application for an apparatus of this type results when the optical equipment is repeatedly out of service due to mechanical damage, making it necessary to look for the causal agent. The test procedure would allow the group of people who could have caused the damage to be narrowly defined. Additionally, with a testing procedure of this type, the sterilization process for the endoscope could be optimized to the extent that the wear and tear which arises even when the endoscope is used properly would be minimized.
2. Description of the Related Art
The previously known methods of preoperative optical quality and functional testing consist of the visual inspection of the optical equipment at the end of the preparatory process, in which the image in the endoscope""s optics is checked by simply peering through it, followed by an examination of the sleeve tube to check for mechanical damage. The drawback to this procedure, however, is the wide range given to the judgment of the person who performs the inspection, as well as the uncertainties which manifest themselves in terms of the gradual changes that are typical for most of the opaqueness caused by wear. As already discussed, lens damage may also occur as a result of mechanical damage, without the latter being noted by a visual examination of the sleeve tube since they occurred within the elastic area of the deformation of these components.
A further traditional test procedure involves determining the degree of transmission of the endoscope. The apparatus used to perform this procedure is comprised of a luminosity meter which is connected to the eyepiece of the endoscope and measures the amount of light which passes through the optics of the endoscope. The values obtained in this manner are then related to a previously measured reference value, and on this basis the degree of transmission of the optics can be determined. It is true that a high degree of transmission, in addition to other qualitative parameters, indicates a good image quality. However, owing to light losses caused by the equipment design, the degree of transmission even of brand-new endoscopes lies below 100%, so that the degree of transmission as a fixed point for the assessment of the quality of a new endoscope must be determined by measurement. It must also be decided when the degree of transmission reaches a point when the endoscope must be considered unusable and can no longer be utilized for further examinations. Thus, only after extensive preparatory efforts does the transmission method offer a selection criteria for rigid endoscopes. In addition, knowing the degree of transmission does not allow the user to differentiate whether transmission losses are caused by cloudiness or lens fractures.
In practice, the optical procedure employed to inspect endoscopes is the use of an ocular microscope. To do so, the endoscope is pointed against a bright, reflective surface to view the eyepiece of the endoscope through the microscope. To create an image of the endoscope""s rod lens surface on the retina in this manner, the optical axes of the eye and of the ocular microscope with respect to the longitudinal axis of the endoscope must be aligned manually. Varying the distances between the endoscope and the microscope while retaining the axis alignment makes it possible to view all of the rod lenses inside the endoscope. The image magnification achieved by means of an ocular microscope allows for the differentiation between lens fractures and dirt particles within the optical system. A disadvantage of the procedure described above, however, is the labor-intensive alignment of the optical axes with respect to the longitudinal axis of the endoscope, to the extent that the results are frequently not repeatable and can only be performed by experienced personnel suffering considerable fatigue.
To determine the quality of endoscopes, the optics industry employs optical benches with commercially available optical components, by means of which the endoscopes can be accurately aligned and examined with respect to the optical axis of an analytical device, such as a camera. These optical components and benches, however, are so costly and unwieldy that their use is impractical at the frequently changing locations where endoscopes are used, such as in hospitals.
It is therefore the objective of the present invention to provide an apparatus which allows for the simple, economical and rapid testing and assessment of the condition of endoscopes, yields repeatable results and can be operated by untrained personnel.
The present invention provides an apparatus or device for inspecting and assessing the condition of endoscopes, such apparatus having a guide into which the endoscope is placed, a lens assembly which forms the eyepiece that is arranged at the proximal end of the guide, and an endoscope support which can be moved inside the guide in the direction of the optical axis of the lens assembly, and which accommodates and holds the endoscope in place.
The apparatus described in this invention makes examining the image quality of endoscopes a simple matter, the movability of the endoscope support along the optical axis rendering any time-consuming and complicated manual alignment unnecessary. The apparatus described in this invention is therefore easy to handle, and even untrained personnel can be assigned to the inspection of endoscopes. In addition, due to the simplified alignment procedure, the inspection results are repeatable, and the manufacturing costs of the apparatus described in this invention are low when compared to the traditional inspection apparatuses described above which also yield repeatable inspection results.
In a preferred embodiment of the apparatus, the guide takes the form of a guide tube, and the endoscope support offers the advantage of being a sliding element in the form of a circular cylinder whose outside diameter conforms to the inside diameter of the guide tube and which has a center opening through which a sleeve tube of the endoscope to be checked is inserted and held in place. To this effect, the inside diameter of the opening appropriately conforms to the outside diameter of the sleeve tube.
The slide element has the advantage of having a groove which extends along its entire length and whose bottom wall hugs a pivoting ratchet wheel inside the guide tube wall, so that the sliding element is connected to the ratchet wheel in such a way that it is frictionally engaged, whereby the ratchet wheel extends circumferentially beyond the guide tube wall, and when manually turned causes the sliding element to move inside the guide tube.
In an advantageous variation of this design, the groove can have an area with a tooth profile and the ratchet wheel can take the form of a toothed wheel which engages in the tooth profile area, whereby the toothed wheel is connected via a shaft and in a torsionally rigid manner to an adjusting wheel located outside the guide tube.
A particularly precise image focus can be obtained if the adjusting wheel shaft is coupled to a drive unit that is mounted to the guide tube and is comprised of an electric motor fed by an energy storage unit, a driving medium, and a spring-loaded push contact which extends from the drive unit and which, when subjected to pressure from outside, such as a manual push, causes the adjusting wheel shaft to be subjected to a turning motion generated by the electric motor, thus causing the sliding element to move inside guide tube.
A useful feature of the guide is that it has at least one recess cut into its tube wall, said recess extending longitudinally starting from the distal end of the guide. In a further enhancement of this design, at least one groove extends all the way through, along the entire guide. In a variation of this embodiment of the apparatus described in this invention, at least one recess extends only as far as the lens assembly.
In a preferred embodiment, the guide and the endoscope support are made of a light-shielding material to minimize any unwelcome incidence of an external light source other than the light which enters the apparatus through the endoscope.
It is also useful for at least one of the lenses in the lens assembly to be a magnifying lens and for the lens assembly to have a focal distance between 5 and 100 millimeters.